Transmissions are widely employed on a wide variety of mechanized devices, including motor vehicles, construction machinery, excavation machinery, small electric motors, and the like. Manual and automatic transmissions, also known as speed changers or torque converters, typically employ gears, hydraulics, or friction to control transfer of torque from a power source to a load.
Conventional transmissions suffer from numerous problems. Transmissions generally have low mechanical and energy efficiencies, particularly when operating over the full range of output power requirements generally required in normal applications. Transmissions typically operate efficiently only at or near the output speeds corresponding to the input-to-output rotational speed ratios designed into the device. Additional mechanical and energy inefficiencies can result from the operational demands for starts, stops, and accelerations. Transmissions generally have slow response times, are bulky and/or heavy, are complex, and/or lack robustness.
Considerable resources have been expended towards developing a more energy efficient and operationally effective transmission system that overcomes these numerous problems. These efforts have been largely unsuccessful due to the need to make unacceptable compromises in cost, weight, and operational complexity to overcome mechanical and/or design limitations.